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scandir.c revision 1.21 
      1 /*	$NetBSD: scandir.c,v 1.21 2001/11/21 00:48:28 enami Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)scandir.c	8.3 (Berkeley) 1/2/94";
     40 #else
     41 __RCSID("$NetBSD: scandir.c,v 1.21 2001/11/21 00:48:28 enami Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 /*
     46  * Scan the directory dirname calling select to make a list of selected
     47  * directory entries then sort using qsort and compare routine dcomp.
     48  * Returns the number of entries and a pointer to a list of pointers to
     49  * struct dirent (through namelist). Returns -1 if there were any errors.
     50  */
     51 
     52 #include "namespace.h"
     53 #include <sys/types.h>
     54 #include <sys/stat.h>
     55 
     56 #include <assert.h>
     57 #include <errno.h>
     58 #include <dirent.h>
     59 #include <stdlib.h>
     60 #include <string.h>
     61 
     62 #ifdef __weak_alias
     63 __weak_alias(scandir,_scandir)
     64 __weak_alias(alphasort,_alphasort)
     65 #endif
     66 
     67 /*
     68  * The DIRSIZ macro is the minimum record length which will hold the directory
     69  * entry.  This requires the amount of space in struct dirent without the
     70  * d_name field, plus enough space for the name and a terminating nul byte
     71  * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
     72  */
     73 #undef DIRSIZ
     74 #define DIRSIZ(dp)							\
     75 	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
     76 	    (((dp)->d_namlen + 1 + 3) &~ 3))
     77 
     78 int
     79 scandir(dirname, namelist, select, dcomp)
     80 	const char *dirname;
     81 	struct dirent ***namelist;
     82 	int (*select) __P((const struct dirent *));
     83 	int (*dcomp) __P((const void *, const void *));
     84 {
     85 	struct dirent *d, *p, **names, **newnames;
     86 	size_t nitems, arraysz;
     87 	struct stat stb;
     88 	DIR *dirp;
     89 
     90 	_DIAGASSERT(dirname != NULL);
     91 	_DIAGASSERT(namelist != NULL);
     92 
     93 	if ((dirp = opendir(dirname)) == NULL)
     94 		return (-1);
     95 	if (fstat(dirp->dd_fd, &stb) < 0)
     96 		goto bad;
     97 
     98 	/*
     99 	 * estimate the array size by taking the size of the directory file
    100 	 * and dividing it by a multiple of the minimum size entry.
    101 	 */
    102 	arraysz = (size_t)(stb.st_size / 24);
    103 	names = malloc(arraysz * sizeof(struct dirent *));
    104 	if (names == NULL)
    105 		goto bad;
    106 
    107 	nitems = 0;
    108 	while ((d = readdir(dirp)) != NULL) {
    109 		if (select != NULL && !(*select)(d))
    110 			continue;	/* just selected names */
    111 
    112 		/*
    113 		 * Check to make sure the array has space left and
    114 		 * realloc the maximum size.
    115 		 */
    116 		if (nitems >= arraysz) {
    117 			if (fstat(dirp->dd_fd, &stb) < 0)
    118 				goto bad2;	/* just might have grown */
    119 			arraysz = (size_t)(stb.st_size / 12);
    120 			newnames = realloc(names,
    121 			    arraysz * sizeof(struct dirent *));
    122 			if (newnames == NULL)
    123 				goto bad2;
    124 			names = newnames;
    125 		}
    126 
    127 		/*
    128 		 * Make a minimum size copy of the data
    129 		 */
    130 		p = (struct dirent *)malloc(DIRSIZ(d));
    131 		if (p == NULL)
    132 			goto bad2;
    133 		p->d_fileno = d->d_fileno;
    134 		p->d_reclen = d->d_reclen;
    135 		p->d_type = d->d_type;
    136 		p->d_namlen = d->d_namlen;
    137 		memmove(p->d_name, d->d_name, (size_t)(p->d_namlen + 1));
    138 		names[nitems++] = p;
    139 	}
    140 	closedir(dirp);
    141 	if (nitems && dcomp != NULL)
    142 		qsort(names, nitems, sizeof(struct dirent *), dcomp);
    143 	*namelist = names;
    144 	return (nitems);
    145 
    146 bad2:
    147 	while (nitems-- > 0)
    148 		free(names[nitems]);
    149 	free(names);
    150 bad:
    151 	closedir(dirp);
    152 	return (-1);
    153 }
    154 
    155 /*
    156  * Alphabetic order comparison routine for those who want it.
    157  */
    158 int
    159 alphasort(d1, d2)
    160 	const void *d1;
    161 	const void *d2;
    162 {
    163 
    164 	_DIAGASSERT(d1 != NULL);
    165 	_DIAGASSERT(d2 != NULL);
    166 
    167 	return (strcmp((*(const struct dirent *const *)d1)->d_name,
    168 	    (*(const struct dirent *const *)d2)->d_name));
    169 }
    170